This is normal. The joint of the necklace cannot be pure gold, because gold is soft and easy to deform. Therefore, the joint of the necklace contains synthetic metal to enhance its strength.

In addition, there is the accuracy of testing equipment, and the results measured by fixed quality equipment are definitely different.

Finally, don't think too much about the gold content when buying jewelry, because gold jewelry in many places is not pure gold. The more beautiful gold jewelry, the lower the gold content, because other metals are needed for decoration and connection.

If you want high gold content, buy jewelry with the simplest processing technology, such as the oldest gold ring, commonly known as the golden hammer.